Internal-combustion engine and exhaust gas turbine therefor



Aug. 15, 1950 K. A. BRowNE 2,518,660

. INTERNAL-cousus'rlou ENGINE AND EXHAUST GAS v'ruRINE THEREEoR Filed Sept. 7, 1944 A 8 Sheets-Sheet 1 ATTDRNEY 8 Sheets-Sheet 2 INTELCOGL E REFOR l. oWNl-z INTERNALfCOMB 'STION ENGINE AND /rllirlll all. i.

INVENToR.

Kennen-e A snuwnc.

ATTDRNLY Angl 15, 195o K. A. BROWN E INTERNAL-COMBUSTION ENGINE AND EXHAUST GAS TURBINE THEREFOR 8 shams-sheet :s

Filed Sept. 7, 1944 INVENTOR. KENNETH A BnnwNE.

'l ATTnRNc- Y K. A. BROWNE 2,518,660 INT1-3mm.-ccmBusTIoN.r ENGINE AND 'EXHAUST GAs TURBINE THEREFoR Aug. 15, 195o Filed Sept. 7, 1944 8 Sheets-Sheet 4 I E *3y-Waag AT TURN EY Aug. l5, 1950 K. A. BRowNE 2,518,660

' INTERNAL-COMBUSTION ENGINE AND EXHAUST GAS TURBINE THEREFoR Filed Sept. 7, 1944 8 Sheets-Sheet 5 KINNs-m Afan-u AT1' l Aug. 15, 195o v K. A. BRowNE 2,518,660 INTERNAL-coususnou ENGINE AND EXHAUST GASTURBINE THEREFOR Fled'SepL 7, 1944 8 Sheets-Sheet 6 INVENTORL L N w D R A H n N N E KY B ATTURNEY Aug. 15, 1950 K. A. BRowNE A 2,513,660

INTERNAL-COMBUSTION ENGINE AND ExmusT GAS TURBINE mREFoR Filed Sept. 7, 1944' 8 Sheets-Sheet 7 INVENTOR. KENNETH A. BRDWNE.

BY wm@ ATT'DRNEY Aug. l5, 1950 K. A.l BRowNE 2.518,66()

INTERNAL-coNBusTIoN ENGINE AND l Emus'r GAS TURBINE mEREFoR Filed Sept. 7, 1944 8 `Sheets-Sheet 8 INVENTOR. l KENNETH A-QHDWNE.

75g/fm@ ATTCIRNEY Patented 15, 1950 lINTERNAL-COMBUS'IION ENGINE AND EXHAUST GAS TURBINE THEREFOR Kenneth A. Browne, Ridgewood, N. J signor to Wright Aeronautical Corporation, a corporation of New York i Application September 7, 1944, Serial No. 553,092

7 Claims.

This inventionrelates to internal combustion engines, and is particularly directed to means for recovering power from the engine exhaust gases.

It is well known that a considerable portion of the power available in the combustion gases of an internal combustion engine isA wasted through its exhaust gases. In the past, the energy in the exhaust gases of an internal combustion engine has been utilized in various ways, for example, 'by means of a turbo-supercharger. However, in a turbo-supercharger, the supercharger output is -conventionally controlled by a waste gate controlling the engine exhaust gases delivered to or byfpassed around the turbine, and in this way, maintaining a substantially constant engine exhaust back pressure. However, because of this back pressure, at least a portion of the energy available in the exhaust gases recovered by the turbo-supercharger is at the expense of engine efficiency. This is particularly true of high altitude operation of aircraft engines. Accordingly, it is an object of this invention to utilize the energy in the engine exhaust gases without adding appreciably to the engine exhaust back pressure.

It is a further object of this invention to use the energy available in the engine exhaust gases for driving a turbine driven fan supplying engine cooling air. The invention further comprises a novel disposition and construction of the turbine-driven fan in an aircraft engine installation. Thus the turbine is coaxially disposed between the engine and propeller driven thereby and the fan is formed integral with the turbine wheel, the fan blades in effect comprising spokes for the turbine wheel. Furthermore, the turbine comprises the novel construction wherein the turbine blades are cast in groups, each group having an inwardly extending supporting arm and being circumferentially expandable relative to the adjacent turbine blade groups. With this construction there are no tangential stresses at the rim of the turbine wheel as a result of thermal expansion of the wheel rim.

It is also an object of this invention to utilize some of the power in the engine exhaust gases by drivably connecting the turbine wheel and/or the aforementioned turbo-fan combination to the engine crank shaft. The turbo-fan may be geared directly to the crank shaft through a xed speedratio transmission. However, since an aircraft engine may have approximately a two to one speed range between full power and minimum cruising operation, the turbo-fan would have a similar two to one. speed range between full power and cruising operation if a xed speed ratio'were provided between the turbine and engine. Also, since the power required by a fan is substantially proportional to the cube of its speed, a two to one fan-speed range would provide an eight to one range in the fan power requirements. This is much too large in view of the c ooling requirements of the engine, and accordingly, it is an object of this invention to provide a. multi-speed ratio transmission between the turbo-fan and engine. It is a further object of this invention to provide means for automatically shifting said transmission to reduce the turbo-fan to crank shaft speed ratio with increase in engine speed. With such a construction the engine speed may be varied without requiring a corresponding change in the speed of the turbo-fan. A two-speed transmission has been provided and in order to prevent hunting of the transmission between its two speed ratios, novel control means are provided whereby there is a substantial speed differential between a speed ratio shift in one direction and the return shift. As the engine speed and power'increase, the rate of discharge of the engine exhaust gases also increases, and therefore, it is a further object of this invention to increase the nozzle discharge area of the turbine nozzle box with increase of engine speed, in order to efficiently use the power available in the engine exhaust gases. In addition, it is a further object of this invention to use the means for shifting the turbo-fan to crankshaft speed ratio for also adjusting thel turbine nozzle box to increase the nozzle discharge area with increase in engine speed.

Instead of or in addition to drivably connecting the turbo-fan to the engine crank shaft, the turbo-fan may be used to provide an air jet propulsive thrust and/or to drive various engine auxiliaries as illustrated in other embodiments of applicants invention. For example, the turbofan may be drivably connected to a supercharger supplying compressed air to the engine induction system. The power available for driving the supercharger may be controlled by varying the engine-cooling-air power demand on the turbofan and in addition or in lieu thereof, the supercharger may be controlled by controllably wasting its output air. As a further modification, the turbine driven supercharger is arranged to over-compress the air, and after passing through an intercooler, the compressed air expands through a socalled Francis or reaction type turbine, drivably connected to the engine, from which the air is distributed to the engine cylinders. 'I'he turbo-fan may also be utilized for driving various engine auxiliaries, e. g., an A. C. alternator, at constant speed. It is a further object of'this invention to provide means to automatically vary the enginecooling-air power demand on a turbo-fan in order to so control the total power demand on the turbo-fan that it operates at a substantially constant speed and therefore drives the engine auxiliary connected thereto at a constant speed.

Other objects of this invention will become apparent upon reading the annexed detailed description in connection with the drawing in which:

Figure 1 is a schematic view partly in section of an internal combustion engine embodying one form of the invention for using the power available in the engine exhaust gases;

Figure 1A is a schematic view of a modification of Figure 1;

Figure 1B is a view taken along line IB--IB of Figure 1A;

Figure 2 is a sectional view of a modied form of the invention;

Figure 3 is a sectional view illustrating automatic cowl nap control means;

Figure 4 is a sectional view illustrating the preferred form of the invention;

Figure 4A is a sectional view taken along lines 4A-4A of Figure 4;

Figures 5 and 6 are sectional views respectively taken along lines 5-5 and 6 5 of Figure 4;

Figure I is an end view of the turbine nozzle construction;

Figure 8 is a sectional view taken along line l-l of Figure 7;

Figure 9 is a sectional view taken along line l-S of Figure 8;

Figure 10 is an end view of a portion of the turbo-fan;

Figure 11 is a sectional view taken along line Il--Il of Figure 10;

Figure l2 is a detail end view of a turbine blade section;

Figure 13 is a sectional view taken along line I3-I3 of Figure 12; and

Figure 14 is a section view taken 'along line I4I4 of Figure 10.

Referring rst to Figure 1, an aircraft engine installation is illustrated comprising a conventional radial cylinder air cooled internal combustion engine i0 which is drivably connected to a. propeller I2 and is disposed within a cowl I4 having an annular air entrance opening I6 and an air exit opening I8 controlled by conventional cowl flaps 20. A combined turbine and fan or turbo-fan 22 is coaxially disposed between the engine and its propeller. The turbofan 2.2 comprises a hub portion 24 'having fan blades 26 extending radially therefrom and a rim portion 28 about the outer perimeter of the fan blades having turbine blades 30 extending radially therefrom. Thus the turbo-fan comprises an integral disc-like rotor in which the fan blades 26 simulate the spokes of a wheel. The engine cylinders 32 each exhaust into an exhaust pipe 34 to an individual nozzle box 38 whence the exhaust gases discharge against the turbine blades 30 to drive the tunbo-fan 22. When the turbo-fan is driven by the engine exhaust gases, its fan blades .26 supply cooling air from the air entrance I6 to and over the engine cylinders 32 in heat exchange relation therewith and this air then discharges through the air exit opening I8. As is conventional construction,

suitable bailles preferably are disposed between the radial cylinders 32 to 4confine the cooling air flow between the cylinders to the conventional cooling fins 31 projecting therefrom.

The individual nozzle boxes 36 are disposed adjacent each other so that together they define an annular nozzle box construction from which the engine 'exhaust gases discharge against the turbine blades 30. The turbo-fan and nozzle box construction is hereinafter more fully de-l scribed. From the turbine blades 30, the exhaust gases enter an annulus 38 whence they discharge rearwardly over the cowl I4. The entrance portion of the cowl is inturned to the leading edge of the turbo-fan inwardly of the turbine -blades 30 and a fairing member 40 provides a streamlined continuation thereof to enclose the nozzle Ibox structure. The inturned leading edge of the coWl and the fairing member 40 are both provided with spring loaded clearance type packing 4I cooperable with an annular ring 43, projecting from both sides of the turbo-fan inwardly of the turbine blades 30 to provide a seal therebetween. Also, the hub of the turbo-fan and propeller is enclosed in a fairing structure to provide a streamlined engine nose structure and a streamlined annular air entrance opening IB.

The energy available in the engine exhaust gases in general is much larger than the enginecooling air power requirements. Thus, the turbo-fan may also be used to pump an air jet out through a discharge orifice controlled by flaps 42 to produce an auxiliary thrust on the aircraft. The opening controlled by flaps 42 is disposed in front of the engine cylinders and therefore the air jet discharging therethrough is in parallelism with the flow of engine cooling air.

In addition, or in lieu of this auxiliary air jet, the extra power available in the engine exhaust gases above the engine cooling air requirements may be also used to drive a supercharger 44. To-

this end the supercharger 44 is provided with an intake duct 46 and operates to supply compressed air through an intercooler 41 to the carburetor 48 whence the compressed air is discharged either directly to the various engine cylinders or to an engine driven supercharger 49 and thence through the intake pipes 50 to the various engine cylinders. The cooling air for the intercooler 41 may also be supplied through the duct 46 and a duct 46. In order to drive the supercharger 44, the turbo-fan is drivably connected to a shaft 52 (as hereinafter described) which in turn is drivably connected to a shaft 54 through suitable bevel gears 56 and a Iuniversal coupling 58. 'I'he shaft 54 is drivably connected to a universal coupling 60 and thence through a suitable multispeed transmission 62, having a shift control arm 63, to the impeller of the turbo-supercharger 44.

The cooling air powerdemand on the turbo-fan varies with the rateof flow of the engine cooling air. 'I'hus for a given fan speed, this power demand increases with increase in the rate of ow of the cooling air until a predetermined peak is reached and then decreases with further increase in the rate of cooling air flow. Preferably the turbo-fan is operated Ibeyond this peak, that is, in the range where an increased flow of engine cooling air results in a decreased power demand. Accordingly, the power demand of the engine cooling air can be varied by adjusting the exit cowl flaps 2li, thereby controlling the speed of the turbo-fan and therefore the speed and outrput pressure of the supercharger 44. In addition to or in lieu-of this cowl flap control, the pressure of the supercharged air delivered to the carburetor 48 may also be controlled by a waste valve 84.

Figure 1A illustrates a further modification in which the entire output of the turbo-supercharger 44 is used, the supercharger 44 being driven from the turbo-fan 22 as in Figure 1. In general there is suillcient energy available in the engine exhaust gases for the supercharger 44 to over-compress the combustion air or charge. In Figure 1A the entire output of the supercharger passes through the intercooler 41 and the carburetor 48 to an annulus 49 from which it expands through the rotor of a reaction or Francis" type turbine As is conventional in turbines of this type, the turbine 5| comprises a rotor having a plurality of vanes 5|' through which the operating fluid expands and the turbine is regulated by suitable adjustable entrance vanes 53, which, e. g., may be adjusted by crank arms 53. From the turbine 5| the charge is delivered to an 'annular manifold 55 whence it is delivered to the various engine cylinders 3.2. The rotor of tur-bine 5| is splined to a shaft 51 which is drivably connected to the engine crankshaft extension 59 through suitable gearing 6| including a one-way clutch 65 which overruns if the engine should tend to drive the turbine.

With the arrangement of Figure 1A, the turbine 5| addsv some power directly to the engine crankshaft through the gearing 6|, but what is more important. the expansion of the charge through the turbine 5| results in an appreciable reduction in temperature of the charge. This reduction in temperature of the engine intake air .or charge has several desirable results: (1) increased density of the charge and therefore greater engine power for a, given intake manifold pressure; (2) allows engine operation at a higher intake manifold pressure and engine power before detonation occurs; and (3) allows engine operation at a lower fuel-air ratio at a given power without detonation than would be possible at a higher temperature of the engine intake air. Obviously the turbine 5| could be used to drive an engine auxiliary instead of being drivably connected to the engine crankshaft. The essential requirement being that after passing through the intercooler 41 the compressed charge expands through a, motor (illustrated as turbine 5|) which does work and in so doing extracts heat from the charge.

'Ihe excess power available in the engine exhaust gases above the engine cooling air power requirements may also be used to drive other engine auxiliaries, e. g., an A. C. alternator. This embodiment of applicant's invention is illustrated in Figure 2 in which the turbo-fan 22 'is similar to that illustrated in Figure 1 and as in Figure 1 is journaled about an axial extension 66 of the nose section 68 of the engine crank case. An engine driven propeller shaft 18 is journaled within the crankshaft nose section 68 and extends through the axial extension 66. The turbofan hub 24 has an axial extension 12 to which a bevel gear 14 is splined. A second bevel gear 16 is supported from the crank case nose section 68 in driving engagement with the bevel gear 14 and a shaft 18 is splined to the bevel gear 15. With this construction, a `portion of the power absorbed by the turbo-fan from the engine exhaust gases supplies the engine cooling air power demand and the balance is transmitted to the shaft 18; In Figure 1 the shaft I2 may have a driving connection to the turbo-fan similar to the driving connection of the shaft 18 in Figure 2.

The shaft 18 is drivably connected to an A. C. alternator 88 which furnishes electric power for the electric equipment of the aircraft or the shaft 18 may be drivably connected to some other engine auxiliary. Preferably the A. C. alternator or other engine auxiliary is driven at a'constant speed. To this end and as described in connection' with Figure 1, the speed ofthe turbo-fan and therefore the engine auxiliary driven thereby may be varied by. controlling the engine cooling air power demand by means of cowl aps 28. Thus if the engine cooling air and A. C. alternator power demand on the turbo-fan increases. the turbo-fan speed and therefore the A. C. alternator speed will decrease. However, by adjusting the cowl flaps 20 in the opening direction to decrease the power demand of the engine cooling air, the turbine speed and therefore the A. C. alternator speed may be restored to its desired value. To this end the cowl flaps 20 may be automatically controlled in response to variations in the speed of the A. C. alternator or in response to variations in the frequency of its output current.

Figure 3 illustrates a simple automatic means for adjusting the cowl flaps 20 to maintain the A. C. alternator 8|! at constant speed. In Figure 3, a hollow'governor shaft 18 is drivably connected to the A. C. alternator and carries flyweights 8| adapted to move outwardly under the action of centrifugal force to raise and lower a valve stem 82 slidably fitted within the hollow shaft 19 against a spring 83. The valve stem 82 is provided with an annular groove 84 which when the valve stem is raised, is adapted to connect a source of engine oil pressure with the cylinder 86 of a hydraulic motor through conduit 81. When the Avalve stem is lowered to close the oil pressure passage 85, a button 88 at the end of the valve stem moves downwardly into a counterbor'ed portion of the hollow shaft 18 to connect the annular groove 84, conduit 81, and hydraulic motor cylinder 86, to the interior of the hollow shaft 18 to drain oil from the hydraulic motor. The piston 89 of the hydraulic motor is connected to the flaps 28 and is spring urged to effect the opening adjustment of the flaps when oil is drained from the motor cylinder 86 in response to a lowering of the valve stem 82 as a result of a decrease in speed of the A. C. alternator. Upon an increase in speed of the A. C. alternator, the valve stem is raised to admit oil pressure to the hydraulic motor and to close the drain connection to the interior of the shaft 19 whereupon the hydraulic motor operates to effect a closing adjustment of the flaps 2|). With this arrangement the cowl flaps 28 are automatically adjusted to vary the engine cooling air power demand on the turbo-fan to maintain a substantially constant speed of the turbo-fan and A. C. alternator driven thereby.

Referring now to Figures 4 to 6, there is disclosed in these figures one embodiment of applicants invention in which the turbo-fan is drivably connected to the engine crank shaft and propeller shaft in order to use the excess power available in the engine exhaust gases over and above the engine cooling air power requirements. In this embodiment, to two-speed transmission is provided between the turbo-fan and the engine crank shaft in order that the engine speed may be varied through a speed range without forcing acorresponding turbo-fan speed range. The turbo-fan designated 22' in Figure 4 is identical to the turbo-fan 22 of Figures 1 and 2 except its' hub 24' has been modified by eliminating the extension 12 and instead providing radially extending splines or serrations 60 about one end of the turbo-fan hub. The turbo-fan hub 24' is loosely iitted over a sleeve 82 of an annular clutch housing 94 and a nut 96 serves to rigidly secure the turbo-fan splines 90 in engagement withcorresponding splines on the clutch housing 84.A With this radial spline constructionI the turbofan is accurately piloted regardless of the expansion of its hub 24. The clutch housing 84 is Journaled about the extension 66 of the crank case nose section 68 and is provided with an annular cylindrical space or hydraulic cell 08 within which a piston is slidable. The clutch housing 64 is provided with splines |02 facing splines |04 on an annular gear |06 spaced outwardly therefrom. vBetween the splines |02 and |04 are disposed a series of clutch plates |08 splined to the clutch housing and an alternate series of clutch plates I0 splined to the annular gear |06. A ring |||-serv es to retain the end clutch plate remote from the piston |00 against axial movement. In addition, the clutch housing is connected to a second annular gear ||2 through a conventional one-way ,clutch ||4 which is adapted to transmit power from the clutch housing to the gear ||2 but not in the reverse direction. The one-way clutch is best seen in Figure 4A in which the arrow indicates the direction of rotation. With this construction the turbo-fan is adapted to be drivably connected to gear |06 or to gear ||2, depending on whether the clutch plates |08 and ||0 are engaged or disengaged.

A plurality of circumferentially spaced double pinions, comprising gears ||6 and ||8 are disposed in meshing engagement with annular gears |06 and I2 respectively. Each of the double pinions ||6, ||8 is secured to a stub shaft |20 by a nut |22. The stub shafts-|20 each extend into the crank case nose section 68 which provides a bearing support therefor. The inner end of each stub .shaft is provided with a pinion gear |24 disposed in engagement with an internal gear |26 drivably splined. to the engine crank shaft |28. A sun gear |30 is secured to the crank case nose section 68 and is spaced radially inward from the internal gear |26. A plurality of circumferentially spaced planet pinions |32 carried by the propeller shaft are disposed between and in meshing engagement with the internal and sun gears |26 and |30 respectively. In this way internal gear |26 is drivably connected to the engine propeller shaft 10 through the `planet pinions |32 and is driven by the engine crank shaft |28 and by the stub shafts |20 which in turn are driven by the turbo-fan.

Engagement and disengagement of the clutch plates |08 and |0 is controlled by the admission and venting of oil pressure from the clutch cylinder V98. Engine oil pressure is transmitted to a valve |36, disposed at the outer periphery of the clutch cylinder 98, from the hollow propeller shaft 10 through suitable radial drillings |3| and |33 formed therein and in the axial extension 66 of the crank case nose section to passage |34 which terminates at the valve |36. The valve |36 is automatically moved outwardly to admit oil pressure intothe clutch cylinder when the engine speed exceeds a predetermined value, thereby effecting engagement of the clutch plates |08 and ||0 to decrease the turbo-fan-t-crankshaft speed ratio and thereby decreasing the speed of the turbo-fan relative to the crank shaft speed. Valve |36 is cup-shaped and comprises two sets of openings |38 and |40. In the position illustrated in Figure 4, the open end of the valve |36 establishes communication through valve openings |40 between the clutch cylinder 86 and a drainpassage |42. Therefore, when the valve |36 moves inwardly to the oil pressure closed position, the clutch oil quickly bleeds out through passage |42 under the action of centrifugal force acting on the oilthereby disengaging the clutch. The oil bleeding out through the passage |42 iinds its way back into the engine crank case through suitable openings in the engine nose section 68. When the valve |36 moves outwardly against the stop plug |44 the vent passage |42 is closed thereby and valve openings |38 are aligned with the oil pressure inlet.passage |34, whereupon oil pressure is admitted to the interior of the valve |36 and thence into the clutch cylinder 38 through valve openings |40. The clutch piston |60 thereupon operates to engage the clutch plates |08 and ||0.

The valve 36 is connected to an annular plate |46 by means of a tongue and groove connection and a bolt |41. The annular valve plate |46 is disposed in the clutch cylinder and is provided with an inner diameter larger than the inner diameter of the clutch cylinder such that the diierence in these diameters is substantially equal to the movement of the valve |36. A spring |46 is disposed in the clutch cylinder so as to urge the valve |36 inwardly to its closed position in which the inner diameter of the valve plate |46 abuts against the inner wall of the annular clutch cylinder 38. The plate |46 and valve |36 are so proportioned that when the valve is in its closed position, as illustrated, the center of gravity indicated at |50 in Figure 5 of the combined plate |46 and valve |36 is spaced from the center of rotation |5| of the clutch on the side of the vvalve |36, whereby the centrifugal force acting on the combined plate and valve urges the valve radially outward to its open position against the force of the spring |48. The function of the spring |46 is to retain the valve |36 in its oil pressure closed position in which the oil pressure is shut off and the clutch 1s vented until the engine speed exceeds a predetermined value, whereupon the effect of centrifugal force acting on the valve |36 and plate |46 overcomes the valve spring |48 and the valve |36 moves radially outward to its open position.

As best seen in Figure 5 the spring |48 is hooplike in form and is disposed within the clutch cylinder 98 with its two ends |52 and |54 anchored to the clutch housing on opposite sides of the valve |36 by pins |53 and |55. The midpoint of the spring loop is connected to the valve plate |46 at a. point diametrically opposite the valve by means of a stud |56 carried by the plate |46. The stud |56 is provided with a slot |58 for receiving a reduced width portion of the spring loop thereby securing the mid-portion of the spring loop to the valve plate. Thus the stud |56 is not only serving to connect the spring |48 to the valve but it also acts to maintain the symmetry of the spring loop relative to the valve path of travel. A guide pin |60, secured to the clutch housing 94 and extending across the annular clutch cylinder 08, passes through a hole in the head|62 of stud |56 to guide the movements of the valve plate |46 and valve |36 in a radial path.

9 The spring |48 is so'shaped the valve |38- is in its radially inward or` closed about the axis of the clutch housing. `and the spring |48 operates Atourge the valve radially in ward to this closed position. This Iconstruction imtiuy that when asiaeco C turbo-fanspeed exceeds 6,000 R. P. and with position the springv loop is substantially circular has the advantage over a conventional coil spring -in its low speed ratio and with the turbo-fan acting against the valvein that. when the valve is closed and the clutch housing is rotated, the eiect of centrifugal force on the Spring merely operatingl between 4,000 and 4,500 R.. P. M.; the g lofoperator can eiect a shift to thehigh ratio by v the resulting change in speed ratio such as vto reduce the turbo-fan speed to 4,500 R.1P. M., the

valve may bev designed so Vthat it does l not snapv inwardly until the Ian speed decreases to 4,000 R. P. M., thereby providing a stable control. At

this pointit should be noted that with the clutch "momentarily reducingthe engine speed and iii tensions the wire of thespring'loo'p and'does not"v lessen the spring force holding theY valve Iclosed.

Thus since the mid'portion -of the spring |48,- which is connected to the valve plate |46, is disposed at right angles to the path of valve-movement, the tension in the spring loop resulting from centrifugal force acting thereon doesnot lessen orcha'nge the spring force on the valve; *However, with a conventional coil spring vacting against the valve, the spring would compressunder centrifugal vforce acting on the spring coilsthemselves. Similarly, af'conventional coil spring valve plate |46 to urge the valve |36 in an.op'en ing direction, would` be impractical since some sort of retaining means would have to be provided to support the spring coils against llateral displacement over` the large centrifugal forces acting thereon and in which event the friction between the spring coils and this retaining means as comthis way obtaining a turbo-fan speed` approxi- I nately between l5,000 and 6,000 R. P. M. Obviously the invention is not limited to these specic Ivalve shifting ispeeds and speed ratios since' ,the particular speeds at which the valve V|36is designed to shiftv and theparticular speed ratios disposed infthe clutch housingwith'its axis'perpendicular to a radial direction and acting on the the clutch |08, I0 disengaged, the one way clutch ||4 prevents'the turboffan'from absorbing power from the engine, e. g., at 'enginestarting or when the engine is acceleratingrapidly. In the past, and as illustrated in Patents 2,110,711 and 2,348,260,the engagement and disengagement of a rotating clutch was. controlled .by admitting oil pressure thereto'by a remotely disposed valve which obviously could be-controlled 'by a suitable ilyweightgovernor. However, with pared to the spring force itself would bey 'exc'esiA `sive, particular at the high rotative speeds fcontemplated bythe present invention. The spring |48 is also designed so that the increase in the spring return force, urging the trifugal force acting fonv the oil in the rotating valve toward its closed position with radially out- Ward movement of the valve, is less than the resulting increase in the centrifugal force acting on the valve. Therefore, withthe speed of the clutch housing increasing-and with the valve in its closed position, as soon as the centrifugal force valve 'exceeds the spring return force the valve will begin to move outwardly, and, bec'ause centrifugal forceincreases more than the spring return force as 'a result of this outward valve movement, the valve immediately snaps -outward-f- 1y to the extreme limit of its travel. Thereupon the prior art construction-it was necessary to provide a continuous, bleed at the `clutch periphery to permit 'the clutch oil to escape when ,the

oilpressure thereto was cut oil,otherwiseA cencitcnwould prevent the e1ut'eh from disengagmg. Therefore, when such a. rotating clutch was engaged,y there was a'continual circulation ofoil through the clutch, and asa result, considerable the clutch oil bleeds or drains therefrom only iiuid pressure is admitted tothe clutch cylinder 98 to eng'age the clutchplates |08 and H0 to reduce theturbo-fan to engine-crank-shaft speed ratio, thereby reducing the speed ratio of the inwardly until the turbo-fan speed dropped a predetermined amount be1ow 6,000 R. P. M. 'For a given spring,`the magnitude ofthis speed differential between the outward and inward valve movements can be increased by providing a larger valve movement' and/or by changing the disposition of the mass of the valve |36 and itsplate |46 lso that their combined center of gravity is moved closer to the axis of rotation. Thus, for the above mentioned speed ratio, the valve |36 may be designed to snap outwardly to effect en-v gagement of the clutch plates |08, ||0 when the when the oil pressure to the clutch cylinder is cut oil'. Accordingly, with the present invention, the clutch piston canbe tightly sealed within the clutch cylinder, e. g., with rubber seals, and accordingly there is no continual circulation o! oil therethrough when the clutch is engaged upon the application o f oil pressure thereto. Therefore, the disposition ofthe clutch control valve |36 as herein described avoids'the sludging diitioned, and as'hereinafter more fully described,

the composite annular nozzle box comprises a plurality of individual nozzle box sections 36, one

Each nozzle box section 36 is ported shaft |66 extending inwardly through an `annular fairing member |68 supported from the crank case nose section 68 and extending forwardly to the outer edge of the turbo-fan hub 24'. 'The inner end of each-shaft'l is'provided with a. crank arm |10 having a pin |12 carried anemobox section 88 and isadapted to extend between fone end of the associated nozzle box section and pins |12 extend. Also, a resilient rubber bushing m is disposed between each boss m and the pin |12 associated therein and extending therethrough. 'With.- this construction, axial moveone of the guide ends therein toclose oi! .the portion of the nozzle opening 2|2 therebetween. Upon rotation of the valve |84 to its open position, as illustrated bythe dotted lines in Flgure8, the exhaust gases can discharge through the enment of the annular member |14 simultaneously tire nozzle opening u2, Each engine cylinder exhausts into an exhaust pipe -"which discharges rubber bushing .|30 permits lthis valve adiustment 10 into an individual nozzle box section 88. In this way there is no danger of one, cylinder dischargadlusts all of the nozzle box'valvs |84. The

Aeven though the ends of the various Acrank arms necessarily move in an arcuate path.

' of circumferentially spaced piston-cylinder hy- I draulic motors are -supported on the crank case l5 .the nozzle box segtions ,Il has a'tongue2l8 atone Y nose section 88. Each of these motors comprises a cylinder |82 and a piston |84 slidable therein .and having a piston, rod |88' extending through a supportingapron |88 into engagement with the annular member |14. A spring '|88 urges the annular member |14 to the right as viewedinJ Figure 4 to its valve closing position. Accord' from the clutch cylinder 88 through passage 82 ing against the back pressure o f'another cylinder i and in addition, the exhaust piping is quite simple and has a minimumy volume. Moreover, each of end. and a groove 2|8 at the other end to providean interlocking connection between adjacent 1 are disposed in 'front of'the composite annular pressure for actuating the piston |84 is supplied in the'clutch housing, passage |84 in the extension 88 of the crank case vnose section 88 land thence through conduit |98. Withthis construction, when oil pressure is admitted to the clutch cylinder 88 through the clutch control lvalve |88 in response toanincrease of the turbo-fan above a predetermined value, oil pressure is simulta.

`neously admitted behind the piston |84 to open the nozzle valves |84 of each nozzle box section, thereby increasing the eil'ective nozzle box discharge area. Similarly, when the turbo-fan speed drops below a predetermined value, and 40 the clutch valve |88`operates to vent the clutch` cylinder 88, the various cylinders |82 are simul.- taneously vented, whereupon the springs |88 operate to close the valves |84 and reduce the size or the nozzle opening.

The turbo-fan and clutch housing 84 are secured against axial movement jot! the extension 88 of the crankcase nose section 88 by'a thrust plate |88 secured to the end of the extension 88.` In addition, an apron memberl 288 is supported by the extension 86 to cover the leading end of the turbo-ian hub 24. Streamlined supporting webs 282 are disposed between the inturned leading edge ofthe cowl 284 and the apron member 288. The cowl 284 diiers from the cowl |4 of for the exhaust gases, the exhaust gases are discharged into an annular collector ring 288 from which they are lead to a suitable discharge open# Figure l in thatinstead of providing an annular A rearwardly directed exhaust exit 88 therethrough nozzle opening, whereby when operating, the hot engine exhaust gases all discharge ythrough the nozzle opening against the turbine -blades 88 to drive this turbo-i'an.' "Thus, the outer periphery o! the turbo-fanis subjectedtoa large temperature range between its-operating and non-operating conditions. 'Accordinglm itis desirable to form the turbine. blades and outer periphery ofv the turbine so as to permit circumferential expansion and contraction of the turbine o'uter periphery without linducing appreciable stresses in the turbo-ian. ,Tothis end the turbine blades 88 are formed or cast in integral groups 228 each comprising a plurality oi' blades 88 and.` each having a tongue 222 on one end and a groove 224 at the other -end Jto provide a 'circumi'erentially ably is equal to the number oi.' fan blades 28 andv each turbine blade group is provided with an inwardly directed tongue portion 228 which is adapted to be received within a circumferentially extending groove 228 at the outer end of its associated fan bladeV 28, and bolts 288 securely fasten these parts together. Each of the fan blades is separately formed or castand their outer ends extend through an annular ring member 48 which is welded or otherwise secured thereto.l The ring `48 is provided with upturned edges `for cooperation with the seals 4| of Figures 1 and 4 respectively. The inner` or root ends of the fan blades preferably are welded to the turbofan hub 24 and holes 284 serve to provide a illlet and 9. As illustrated, each nozzle box section 88 comprises a chamber having an arcuate nozzle opening 2| 2. with a plurality of spaced guide vanes 2 4 that extend thereacross. Each valvemember |84 is disposed within the chamber of a nozzle between the root ends of adjacent fan blades. The cylindrical wall deilned by each Ioi' holes 284 extends at least to the center of the weld 288,

that is, to the inner end of the root ends of the adjacent fan blades and extends 'outwardly beyond the weld 288, as illustrated in Iiigurell.y In the absence of holes 284, the'weld would extend across the dividing plane between the'root ends of adjacent fanb1ades and as arult cracks would tend to form in the weld in these planes. Also as previously described, the turbo-fan hub 24' is provided with splines or serrations 88 forl drivably connecting the turbo-fan .to the clutch housing ll. With the aforedescribed construction of the turbo-fan, the fan blades 26 in eiect comprises spokes of the turbo-fan wheel 22 or 22 with the turbine blades supported in circumferentially slidable integral groups at the turbo-fan periphery.

At this point it should be noted that although the various embodiments of the invention have been illustrated in connection with a tractor type aircraft propeller installation, it should be obvious that these embodiments can also be applied to a pusher type aircraft propeller installation.

While I have described my invention in detail in its present preferred embodiment, it will be obvious to those skilled in. the art, after understanding my invention, that various changes and modifications may be made therein without departing from the spirit or scope thereof. I aim in the appended claims to cover all such modications.

I claim as my invention:

1. In combination, an internal combustion engine, a turbine arranged to be driven by the engine exhaust gases, a multi-speed transmission drivably connecting said turbine to said engine, and speed responsive means automatically operative to decrease the turbine to engine speed ratio when the speed of said turbine exceeds a predetermined value.

2. In combination. an internal combustion engine, a crankshaft therefor, an adjustable turbine nozzle through which the engine exhaust gases discharge, a turbine arranged to be driven by said exhaust gases, a multi-speed transmission drivably connecting said turbine to said crankshaft, and speed responsive means automatically operative, when the turbine speed exceeds a predetermined value, to decrease the turbine to crankshaft speed ratio and to increase the effective discharge area of said turbine nozzle.

3. In combination, an internal combustion engine, a crankshaft therefor, engine cooling fan means, an adjustable turbine nozzle through which the turbine exhaust gases discharge, a turbine arranged to be driven by the engine exhaust gases. said turbine being drivably connected to said engine cooling fan means, a multispeed transmission drivably connecting said turbine to said crankshaft, and speed responsive means automatically operative, when the turbine speed exceeds a predetermined value, to decrease the turbine to crankshaft speed ratio and to increase the eifective discharge area of said turbine nozzle.

4. In combination, an, internal combustion engine, a crankshaft therefor, an engine cooling fan, a turbine driven by the engine exhaust gases for driving said fan, a multi-speed transmission drivably connecting said turbine to said crankshaft, and means automatically responsive to increase of turbine speed above a predetermined value for shifting said transmission to reduce the turbine to crankshaft speed ratio.

5. In combination, an' internal combustion engine, a crankshaft therefor, an engine cooling fan, a turbine arranged to be driven by the engine exhaust gases for driving said fan, and a multi-speed transmission drivably connecting said turbine to said crankshaft, said transmission comprising a one-wayclutch adapted to provide a high turbine to crankshaft speed ratio, and a device loadable to provide a low speed ratio drive from said turbine to said crankshaft in parallel to said one-way clutch.

6. In combination, an internal combustion engine, a fan for supplying said engine with cooling air, a turbine driven by the engine exhaust gases for driving said fan, means drivably connecting said turbine to an engine auxiliary, and speed responsive means automatically operative for varying the power required to drive said fan in order to regulate the speed of said turbine and engine auxiliary.

7. In combination: a combustion engine; a turbine arranged to be driven by the engine exhaust gases; a. supercharger for supplying the engine with compressed air; means providing a driving connection between said turbine and supercharger; a second turbine arranged to be driven by said air, said second turbine being rotatable independently of said rst turbine and supercharger; and means providing a driving connection from said second turbine to said engine, said last-mentioned driving connection including one-way drive means for transmitting torque from said second turbine to the engine but not inthe reverse direction,

KENNETH A. BROWNE.

REFERENCES CITED The following references are of record in the file of this patent:

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